"As the President has said, we will never be able to eradicate every act of evil in this country, but if we can save any one child's life, we have an obligation to try when it comes to the scourge of gun violence," he said.

The number of murders in Chicago surged above 500 in 2012. There have already been 42 killings in the city this month - more than in any January in over a decade.